1 /*      $OpenBSD: inet_ntop.c,v 1.5 2002/08/23 16:27:31 itojun Exp $    */
   2 
   3 /* Copyright (c) 1996 by Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
  10  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  11  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  12  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  13  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  14  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  15  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  16  * SOFTWARE.
  17  */
  18 
  19 #include "includes.h"
  20 
  21 #ifndef HAVE_INET_NTOP
  22 
  23 #if defined(LIBC_SCCS) && !defined(lint)
  24 #if 0
  25 static char rcsid[] = "$From: inet_ntop.c,v 8.7 1996/08/05 08:41:18 vixie Exp $";
  26 #else
  27 static char rcsid[] = "$OpenBSD: inet_ntop.c,v 1.5 2002/08/23 16:27:31 itojun Exp $";
  28 #endif
  29 #endif /* LIBC_SCCS and not lint */
  30 
  31 #include <sys/param.h>
  32 #include <sys/types.h>
  33 #include <sys/socket.h>
  34 #include "fake-socket.h"
  35 #include <netinet/in.h>
  36 #include <arpa/inet.h>
  37 #ifndef HAVE_CYGWIN
  38 #include <arpa/nameser.h>
  39 #endif
  40 #include <string.h>
  41 #include <errno.h>
  42 #include <stdio.h>
  43 
  44 #ifndef IN6ADDRSZ
  45 #define IN6ADDRSZ   16   /* IPv6 T_AAAA */                 
  46 #endif
  47 
  48 #ifndef INT16SZ
  49 #define INT16SZ     2    /* for systems without 16-bit ints */
  50 #endif
  51 
  52 /*
  53  * WARNING: Don't even consider trying to compile this on a system where
  54  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
  55  */
  56 
  57 static const char *inet_ntop4(const u_char *src, char *dst, size_t size);
  58 static const char *inet_ntop6(const u_char *src, char *dst, size_t size);
  59 
  60 /* char *
  61  * inet_ntop(af, src, dst, size)
  62  *      convert a network format address to presentation format.
  63  * return:
  64  *      pointer to presentation format address (`dst'), or NULL (see errno).
  65  * author:
  66  *      Paul Vixie, 1996.
  67  */
  68 const char *
  69 inet_ntop(af, src, dst, size)
  70         int af;
  71         const void *src;
  72         char *dst;
  73         size_t size;
  74 {
  75         switch (af) {
  76         case AF_INET:
  77                 return (inet_ntop4(src, dst, size));
  78         case AF_INET6:
  79                 return (inet_ntop6(src, dst, size));
  80         default:
  81                 errno = EAFNOSUPPORT;
  82                 return (NULL);
  83         }
  84         /* NOTREACHED */
  85 }
  86 
  87 /* const char *
  88  * inet_ntop4(src, dst, size)
  89  *      format an IPv4 address, more or less like inet_ntoa()
  90  * return:
  91  *      `dst' (as a const)
  92  * notes:
  93  *      (1) uses no statics
  94  *      (2) takes a u_char* not an in_addr as input
  95  * author:
  96  *      Paul Vixie, 1996.
  97  */
  98 static const char *
  99 inet_ntop4(src, dst, size)
 100         const u_char *src;
 101         char *dst;
 102         size_t size;
 103 {
 104         static const char fmt[] = "%u.%u.%u.%u";
 105         char tmp[sizeof "255.255.255.255"];
 106         int l;
 107 
 108         l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]);
 109         if (l <= 0 || l >= size) {
 110                 errno = ENOSPC;
 111                 return (NULL);
 112         }
 113         strlcpy(dst, tmp, size);
 114         return (dst);
 115 }
 116 
 117 /* const char *
 118  * inet_ntop6(src, dst, size)
 119  *      convert IPv6 binary address into presentation (printable) format
 120  * author:
 121  *      Paul Vixie, 1996.
 122  */
 123 static const char *
 124 inet_ntop6(src, dst, size)
 125         const u_char *src;
 126         char *dst;
 127         size_t size;
 128 {
 129         /*
 130          * Note that int32_t and int16_t need only be "at least" large enough
 131          * to contain a value of the specified size.  On some systems, like
 132          * Crays, there is no such thing as an integer variable with 16 bits.
 133          * Keep this in mind if you think this function should have been coded
 134          * to use pointer overlays.  All the world's not a VAX.
 135          */
 136         char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
 137         char *tp, *ep;
 138         struct { int base, len; } best, cur;
 139         u_int words[IN6ADDRSZ / INT16SZ];
 140         int i;
 141         int advance;
 142 
 143         /*
 144          * Preprocess:
 145          *      Copy the input (bytewise) array into a wordwise array.
 146          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 147          */
 148         memset(words, '\0', sizeof words);
 149         for (i = 0; i < IN6ADDRSZ; i++)
 150                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 151         best.base = -1;
 152         cur.base = -1;
 153         for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
 154                 if (words[i] == 0) {
 155                         if (cur.base == -1)
 156                                 cur.base = i, cur.len = 1;
 157                         else
 158                                 cur.len++;
 159                 } else {
 160                         if (cur.base != -1) {
 161                                 if (best.base == -1 || cur.len > best.len)
 162                                         best = cur;
 163                                 cur.base = -1;
 164                         }
 165                 }
 166         }
 167         if (cur.base != -1) {
 168                 if (best.base == -1 || cur.len > best.len)
 169                         best = cur;
 170         }
 171         if (best.base != -1 && best.len < 2)
 172                 best.base = -1;
 173 
 174         /*
 175          * Format the result.
 176          */
 177         tp = tmp;
 178         ep = tmp + sizeof(tmp);
 179         for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) {
 180                 /* Are we inside the best run of 0x00's? */
 181                 if (best.base != -1 && i >= best.base &&
 182                     i < (best.base + best.len)) {
 183                         if (i == best.base) {
 184                                 if (tp + 1 >= ep)
 185                                         return (NULL);
 186                                 *tp++ = ':';
 187                         }
 188                         continue;
 189                 }
 190                 /* Are we following an initial run of 0x00s or any real hex? */
 191                 if (i != 0) {
 192                         if (tp + 1 >= ep)
 193                                 return (NULL);
 194                         *tp++ = ':';
 195                 }
 196                 /* Is this address an encapsulated IPv4? */
 197                 if (i == 6 && best.base == 0 &&
 198                     (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
 199                         if (!inet_ntop4(src+12, tp, (size_t)(ep - tp)))
 200                                 return (NULL);
 201                         tp += strlen(tp);
 202                         break;
 203                 }
 204                 advance = snprintf(tp, ep - tp, "%x", words[i]);
 205                 if (advance <= 0 || advance >= ep - tp)
 206                         return (NULL);
 207                 tp += advance;
 208         }
 209         /* Was it a trailing run of 0x00's? */
 210         if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) {
 211                 if (tp + 1 >= ep)
 212                         return (NULL);
 213                 *tp++ = ':';
 214         }
 215         if (tp + 1 >= ep)
 216                 return (NULL);
 217         *tp++ = '\0';
 218 
 219         /*
 220          * Check for overflow, copy, and we're done.
 221          */
 222         if ((size_t)(tp - tmp) > size) {
 223                 errno = ENOSPC;
 224                 return (NULL);
 225         }
 226         strlcpy(dst, tmp, size);
 227         return (dst);
 228 }
 229 
 230 #endif /* !HAVE_INET_NTOP */
 231 
 232 #pragma ident   "%Z%%M% %I%     %E% SMI"